Historically dairies, breweries, and soft drink bottlers were involved in washing glass bottles in hot caustic solutions using tap water. The metal ions, usually calcium and magnesium, in these solutions tended to form insoluble precipitates that would deposit on the glassware as well as on the equipment used. Sequestering agents known as chelates were added to the washing compounds to keep the metal ions in solution and thus, prevent the undesirable deposits from forming.
An inexpensive chelating agent that is most satisfactory for applications in solutions with a high pH is sodium glucoheptonate. This chelate is prepared by reacting glucose with sodium cyanide in a Kiliani-Fisher reaction producing a nitrile which is subsequently hydrolyzed to form the salt of glucoheptonic acid. Much research has been carried out in the last 30 years with the goal of developing inexpensive chelates that could be used in a wide variety of application.
The majority of this work centered on using 6 or 7 carbon atom sugars but price and sequestering ability made the hexoses the most common starting materials. Most inventions were aimed at the glass washing trade with the purpose of removing undesirable metal ions from the alkaline medium but Arthur Holstein perceived that compounds containing chelated metal ions would be attractive to a different market. His U.S. Pat. (No. 2,943,100) protected the methods of preparing the heavy metal salts of alpha and beta glucoheptonates. The methods presented in his disclosure involved using pentoses, hexoses, invert sugars, or the carbohydrate mixture obtained from thermally hydrolyzed lignocellulose as the starting sugars. The only mixtures of sugars that he reported resulted from hydrolyzing invert sugars. For example, cane sugar would yield equal quantities of glucose and fructose. Karabinose (U.S. Pat. No. 3,217,034) also worked with invert sugars comparing the sequestering ability of the gluconates, glucoheptonates, fructoheptonates, and equal mixtures of glucoheptonates and fructoheptonates produced from invert sugar.
This research on sugar acids led to the industrial production of large amounts of these sequestering agents that found uses in a variety of applications that ranged from cement additives and textile finish additives to bottle washing compounds. The chelated iron compound was used as a micronutrient in some agricultural applications.